Method and apparatus for hydraulic transportation of mined coal

ABSTRACT

A method and apparatus for hydraulic transportation of mined coal from a plurality of mining sites in an underground mine to a station at the surface of the mine is disclosed wherein mined coal is combined with a carrier liquid, cleaned by removal of waste coal tailing therefrom, combined with similarly cleaned coal at a junction box centrally located within the mine, pumped to the surface station, and separated from the carrier liquid. Waste coal tailings are hydraulically transported to a sump where they are separated from the carrier liquid. Carrier liquid used to carry waste coal is returned to the station where it is combined with carrier liquid from the clean coal operation and the aggregate liquid is recycled to the mining sites for further use in hydraulic transport.

United States Patent Leasure Dec. 9, 1975 METHOD AND APPARATUS FOR1,179,883 10/1964 Germany 299/8 HYDRAULIC TRANSPORTATION OF MINE!) COALPrimary Exammer-Ernest R4 Purser [76] Inventor: William C. Leasure, 4130Dumess Asst-5mm wm p pate 1" Houston 77025 Attorney, Agent, orFirm-Larson, Taylor & Hinds [22] Filed: Dec. 7, 1973 [21] Appl. No.:422,799

{57] ABSTRACT [521 US. Cl. 299/8; 299/11; 299/18;

302/14 A method and apparatus for hydraulic transportation {51] Int. Cl.E21C 35/20 Of mined Coal from H plurality of mining Sims in an {53} Fild of S h 299/7 3 [7 18 1 1 derground mine to a station at the surfaceof the mine is disclosed wherein mined coal is combined with a [56]References Ci d carrier liquid, cleaned by removal of waste coal tailingUNITED STATES PATENTS therefrom, combined with similarly cleaned coal ata A junction box centrally located within the mine, 550,051 11/1895McKlnlay 299/7 p p to the Surface station, and Separated from the:1,040,679 10/1912 Hoadley 299/7 L404H2 H1922 Goebl at al" 299/17 carrierl1qu1dw Waste coal tailmgs are hydraullcally 3160548 7/1966 Reichl U299/18 transported to a sump where they are separated from 3,459,0038/1969 ONeal 1 299/11 4 the carrier liquid. Carrier liquid used to carrywaste 3,542,432 11/1970 McCraken... 299/18 coal is returned to thestation where it is combined 3,790,214 2/1974 Kilroy 299/8 with carrierliquid from the clean coal operation and 3. 5990 1 1/1974 McCain 1 1 1 1A 1. 299/1 3 the aggregate liquid is recycled to the mining sites for3,870,373 3/1975 Doerr et al. 1. 299/18 X f h use in hydraulic transportAustralia 299/18 8 Claims, 3 Drawing Figures Sheet 2 0f 3 3,924,895

U.S. Patent Dec. 9, 1975 METHOD AND APPARATUS FOR HYDRAULICTRANSPORTATION OF MINED COAL BACKGROUND OF THE INVENTION This inventionrelates generally to a method and apparatus for transportation of minedcoal from continuous mobile mining machines to a surface station outsidethe mine, and particularly to hydraulic transportation by use of acarrier liquid and recycling of the carrier liquid to the mining site.

In any mining operation wherein continuous mobile mining machines areused a prime requisite must be the quick and efficient removal of coalas it is mined keeping pace with the machine so as not to impede theoperation.

Conventional methods for transportation include loading newly mined coalonto shuttle cars which transport the coal a short distance from themining site to conveyors. These conveyors are linked to centrallylocated rail haulage systems which in turn provide transport to thesurface. Since only coal particles of at least a given size areeconomically useable the waste tailings must be separated from the coalat the surface to provide clean coal for transport to the distributor.

Methods have been proposed which include elimination of the shuttle carhaulage system by utilizing endless conveyors suitably linked so as toprovide continuous transport from the mining machines to the centralrail haulage system and it has also been proposed to eliminate the railhaulage system altogether by means of conveyors from the mining machineto the surface.

Since all of these methods involve relatively complex interrelatedsystems, it will be readily apparent that a breakdown or stoppage at onepoint in the system will result in costly delays to the producer.

In order to overcome these disadvantages, it has been proposed in US.Pat. No 3,260,548, for example, to employ a hydraulic method oftransport wherein coal is transported from the mining machine to amobile slurry preparation terminal where it is comminuted and mixed witha carrier liquid to form a slurry. The slurry is then transported alongflexible conduits to a central underground relay station where it isfurther comminuted and then transported along conduits to the surface.Carrier liquid is separated from the coal and returned to the miningoperation.

While the method employed in the aforesaid patent has eliminated some ofthe enumerated problems, the separating of useable coal from waste isachieved at the surface at a separate processing station distantlylocated from the mine before it can be distributed to consumers.

SUMMARY OF THE INVENTION The present transportation system contemplatesa novel method and apparatus for hydraulic transportation of clean coalfrom a plurality of mining sites to a surface station of an undergroundmine, wherein coal dislodged by a plurality of mine faces by continuousmobile mining machines is transported by means of bifurcated conveyorsto mobile slurring devices. Coal is crushed as it enters the slurryingdevices and falls into bins where it is mixed with a carrier liquid toform a slurry. Slurries thus formed are transported along flexihlcconduits to a series of cleaning tables where waste coal slurries andclean coal slurries are formed by separation of waste coal particles. ortailings along with a part of the water from the slurry. Clean coalslurries are transported along clean coal conduits to a junction boxwherein they are combined to form an aggregate slurry. The waste coalslurries are transported to a sump wherein waste coal tailings areseparated. The aggregate clean coal slurry is transported along aconduit to a station at the surface of the mine where the slurry is v vseparated into its clean coal and carrier liquid components. Remainingliquid from the waste coal slurry is pumped from the slurry upwardlyalong a conduit to a series of stepped settling ponds wherein any coalparticles remaining in suspension in the waste coal carrier liquid areallowed to settle out of the liquid. Remaining liquid is fed by force ofgravity to a stream feeding the station at the surface. At this station.carrier liquids remaining from the clean coal and waste coal slurriesare combined and returned along a conduit to the junction box where theyare redistributed along conduits to the mining sites for further use inthe transportation systern.

It is object of this invention to provide a novel method and apparatusfor hydraulic transportation of coal wherein waste coal is separatedfrom clean coal at a point near the mining site within an undergroundmine, and clean coal only is transported to the surface.

Another object of this invention is to provide a novel method andapparatus for hydraulic transportation of waste coal away from themining area to a centralized location within the mine for wastedistribution.

Yet another object of this invention is to provide a novel method andapparatus for hydraulic transportation of mined coal wherein the carrierliquids used for transport of both clean coal and waste coal areseparated from the coal, combined, and recycled to be used again in themining operation.

Still another object of this invention is to provide a novel method forseparation of waste coal particles from the carrier liquid.

Various means for practicing the invention and other advantages andnovel features thereof will be apparent from the following detaileddescription of an illustrative preferred embodiment of the invention.reference being made to the accompanying drawings.

DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. I is a block diagram illustrating the coal transportation andcarrier liquid recycling systems of the invention within and at thesurface of a coal mine.

FIG. 2 is a perspective view illustrating the continuous miner andslurrying device of the instant invention.

FIG. 3 is a plane view partly in section illustrating the internaltransportation system in an underground mine.

Referring to FIG. 1, there is shown a block diagram of a section of acoal mine and surface thereof. in which coal dislodged from a pluralityof mine faces by continuous mobile mining machines 1 is transported bymeans of bifurcated conveyors 2 to mobile slurrying devices 3. Atslurrying device 3 coal is comminuted by means of crushers mountedthereon and the coal mixed with a carrier liquid, such as. for example.water to form a Slurry. Slurries thus formed are pumped along flexibleconduits 4 to cleaning tables 5 wherein waste coal tailings areseparated from the slurries by any conventional means. for example.horizontally disposed screens within tables 5 having apertures of adiameter such that coal particles of a size deemed unsuitable forfurther processing fall through the screens and are mixed with a part ofthe water from the slurries enter ing cleaning tables from conduits 4 toform waste coal slurries. Waste coal slurries thus formed exit cleaningtables 5 along conduits 6 to a common sump 7 wherein waste coal tailingsare separated from the water. Clean coal slurries are formed by removalof waste coal tailings in cleaning tables 5 and exit tables 5 alongconduits 8 to a junction box 9 centrally located within the mine so asto provide a common source for transport of clean coal to a surfaceprocessing station l. Conduit 10 is provided for removal of clean coal.remaining in slurry form, from junction box 9 to surface processingstation 1 by means of conventional pumps situated at junction box 9. Theslurry is separated at station ll into clean coal and water byconventional means will known in the art. The remaining water. augmentedby water from an additional source, such as a stream 12 fed by recycledwater from the waste coal slurry as hereinafter de scribed, is returnedto junction box 9 via conduit 13 where it is redistributed alongconduits l4 and 15 to continuous miners l and slurrying devices 3 forfurther transportation of coal.

Water remaining from separation of waste coal tailings from the wastecoal slurry at sump 7 is pumped by suitable pumping means, locatedwithin sump 7, upwardly along conduit 16 to a plurality settling pondsl7, X9, 21 located above the mine. Settling ponds l7, 19, 21 are locatedin stepped relationship to each other and interconnected by means ofpiping 18, such that water from pond 17 is fed by force of gravity topond l9 and water from pond 19 is similarly fed to pond 21. Settlingponds l7, l9 2] serve further to separate any coal particles notseparated at sump 7 such that water flowing by force of gravity from anoutlet 22 of settling pond 21 to stream l2 enters stream l2 in arelatively purified condition for recycling to the mining operation.Settling ponds l7, l9, 2] are provided due to the greater degree ofdifficulty in removing waste coal tailings of small particle size fromthe waste coal slurry than that encountered in separation of crushedcoal from the clean coal slurry.

Referring now to FIG. 2, a slurrying device generally designated 3 isattached to a continuous mining machine well known in the art andgenerally designated at l by means of a bifurcated chute conveyor 2having a forward portiori'Zl which includes a belt-type conveyor alsowell known in the art. Forward portion 21 of chute conveyor 2 projectsrearwardly of continuous miner 1 and comprises an extension of frame 23of continuous miner l. Extending longitudinally rearward from forwardportion 2 of chute conveyor 2 are female flanged extensions 24 curved soas to mate with male flanged extensions 25 extending longitudinallyforward of rearward portion 22 of chute conveyor 2. Flanged extensions24 and 25 are mated so as to provide connection between forward portion21 and rearward portion 22, thus forming a continuous path along chuteconveyor 2 between continuous miner l and slurrying device 3. Rearwardportion 22 overlaps forward wall 26 of slur rying device 3 and is heldin mating engagement with wall 26 by means of a flange 27 curveddownwardly from the underside 28 of rearward portion 22. Thus forwardmotion is imparted to slurrying device 3 from the forward motion ofcontinuous miner 1 through conveyor 2.

Slurrying device 3 comprises an open box-like structure generallydesignated at 29 having a front wall 26, two side walls 30, a rear wall31, and a bottom (not Shown). ('ontinuous belt tracks 32 of a type wellknown in the art are moveahly mounted by conventional means to sidewalls 30.

A crusher. generally designated at 33 is fixedly mounted to side wallswithout box-like structure 29. Crusher 33 comprises a crusher drum 34covered over its surface by pointed projections 35 and the drum isrotatably mounted along an axis perpendicular to the axis of side walls30 of structure 29, by means of a shaft (not shown) driven by a motor36. Surrounding crusher drum 34 is a crusher box 37 fixedly mounted toside walls 30 by means of supports 38.

Jets of water 39 are supplied to crusher wheel 34 through apertures 40longitudinally spaced along a pipe 41 horizontally mounted severalinches above wheel 34. Pipe 41 is a continuous length of pipe curved atboth ends so as to form two vertical sections 42 and a horizontalsection 43 which is perforated at regular intervals to form apertures40. Vertical sections 42 of pipe 41 are fixedly mounted to side walls30.

A supply of water is fed to pipe 41 by means of a flexible branchconduit 44 joining a flexible supply conduit 45 at a valve connector 46.Supply conduit 45 also supplies water to the rearward portion 23 ofcontinuous miner 1, Supply conduit 45 is supported along the wall of theunderground mine by means of support hooks 47.

Projecting rearwardly of slurrying device 3 is a flexi ble dischargeconduit 48 centrally mounted to the rear walls 31 of structure 29. Avalve 49 is provided at the junction of discharge conduit 48 and rearwall 31, to regulate the flow of coal water slurry 50 formed instructure 29.

Slurry 50 is formed in the following manner. Coal 51 dislodged from amine face 52 by continuous miner l is fed through hinged doorway 53 tothe forward portion 21 of chute conveyor 2. The movement of coal 50along its path in conveyor 2 is facilitated by means of water fedthrough supply conduit 46. As the coal 50 is discharged from rearwardportion 22 of conveyor 2, it drops onto revolving crusher wheel 34 andis crushed between projections 35 and the walls of crusher box 37. Asthe above described crushing action takes place. jets of water 39 carrythe coal off the crusher wheel 34. maintaining projections 35 free ofcaked coal. The coal water mixture, or slurry 50 thus formed, flows fromthe crusher area and into the rearward portion of slurrying device 3.From slurrying device 3, the slurry 50 is discharged through dischargeconduit 48. This can be accomplished by means of pump 54 though agravity fed method would be within the scope of the invention.

Referring now to FIG. 3, coal removal from a plurality of miningstations is shown wherein coal at mine faces 52 is dislodged bycontinuous miners 1, transported by means of chute conveyors 2 toslurrying devices 3 and slurried as described above, The slurry 50 thusformed is pumped from slurrying device 3 through discharge conduit 48 tocleaning tables, generally designated 5 wherein slurry 50 is separatedinto a clean coal slurry and a waste coal slurry. Cleaning tables 5 arecomprised of a plurality of end connected units 55, 56, 57, 58 placedlongitudinally in the direction of the flow of slurry .50. Units 55, 56,57, 58 are similar in construction and operation with the exception thatthey are constructed in stepped relationship to one an other such thatthe forwardly progressing slurry is caused to overflow from one unitinto the next. Separa tion of slurry 50 into clean coal and water coalslurries can be accomplished by means well known in the art. One methodfor separation would be the use of screens horizontally disposed withineach stepped unit, each screen having holes of sufficient diameter toallow pas sage of coal tailings of a size considered to be waste in theoperation. In operation slurry 50 passes from conduit 48 into unit 55 ofcleaning tables 5 where a part of the waste tailings and water containedwithin slurry 50 are separated resulting in the formation of aseparately advancing waste coal slurry beneath an advancing clean coalslurry. Each slurry then passes through successive stepped units 56, 57,58 with further separation of waste coal tailings in each unit.

Clean coal slurries pass from units 58 of cleaning tables into cleancoal conduits 59, extending from units 58 to a junction box, generallydesignated 9, centrally located so as to receive clean coal slurriesfrom a plu rality of separate mining operations. Junction box 9comprises an inner box 61 nested within an outer box 62, An aggregateslurry 63 is formed within inner box 61 from the discharge of clean coalslurries from con duits 59, so as to provide a single source from whichtransportation of clean coal to the surface of the underground mine caneasily be effected. Thus, aggregate slurry 63 is pumped through port 64of inner box 61 by means of a discharge pump 65 into a conduit 66 whichconnects inner box 61 with a coal removal station (not shown) whereclean coal is separated from its carrier water and the water is returnedfor reuse in the mining operation along a return conduit 67. Recycledwater from return conduit 67 empties into outer box 62 of junction box 9for redistribution. A plurality of return pumps 68 effect redistributionof clean water along supply conduits 45 to continuous miners 1 andslurrying devices 3.

Waste coal slurries exit units 58 of cleaning tables 5 into a pluralityof waste coal conduits 60 for transfer to a sump, generally designated69, where waste coal tailings are separated from carrier water. Wastecoal conduits 60 merge at a point 71 with a single discharge conduit 72for transfer to sump 69. Sump 69 comprises a generally circular pit 74narrowing to form an elongated entrance passageway 75. A plurality offilter screens 77, 78, 79, 80 are vertically disposed along passageway75 to provide means for separation of waste coal tailings from wastecoal slurry 76 as it exits dis charge opening 73 of conduit 72. Screens77, 78, 79, 80 can be provided with openings of decreasing diameter withscreen 77 of conduit 72 having apertures of a diameter large enough topass most of the tailings in waste coal slurry 76, and screen 80disposed nearest the opening into pit 69, having apertures small enoughto block most of tailings, thus providing an even distribution oftailings within passageway 75, and water 81 substantially free oftailings in pit 74.

A pump 82 is provided at the bottom of circular pit 74 of sump 69, forrecirculation of water 81 separated from waste coal slurry 76. Connectedto pump 82 is a conduit 83 for transfer of water 81 to settling ponds(not shown) located outside the underground mine.

Thus it can be seen that there is provided according to the presentinvention a method and apparatus for continuous mining wherein the coalis crushed, screened and sorted within the mine. the clean coal beingtransported by a slurry within the mine to the surface. The tailings areseparated from the carrier liquid within the mine and the carrier liquidis filtered and recirculated.

Obviously many modifications and variations of the present in ention arepossible in light of the above teachings.

What is claimed as new and is desired to be secured by Letters Patentis:

l. A method for transporting mined coal from a plu rality of workingfaces of an underground mine to a station at the surface of said minecomprising the steps Ofl dislodging said coal from said working faces bymeans of a mobile underground mining machine; combining said coal withcarrier liquid adjacent said working faces;

conveying said mined coal and carrier liquid by means of bifurcatedconveyors to crushcrs fixedly mounted to modile slurrying devices;

crushing said mined coal;

admixing said crushed coal with additional carrier liquid to formslurries within said slurrying devices: transporting said slurries tosaid cleaning tables; forming clean coal slurries and waste coalslurries within said cleaning tables by removing waste coal and a partof said carrier liquid from said slurries by I screening meanshorizontally disposed within said cleaning tables, such that clean coaland a part of said carrier liquid remain above said screens and wastecoal and a part of said carrier liquid fall below said screens;

pumping said clean coal slurries along conduits from said cleaningtables to a junction box centrally located within said underground mine;

admixing said clean coal slurries within said junction box to form anaggregate slurry;

pumping said aggregate slurry along a conduit from said junction box tosaid station at the surface of said underground mine by means of a pumplocated adjacent said junction box;

separating said slurry into clean coal and carrier liquid;

pumping said waste coal slurries along conduits away from said cleaningtables and joining said conduits with a single conduit leading to theentrance passageway of a Sump so as to an aggregate waste coal slurry;

pumping said aggregate waste coal slurry from said single conduit intosaid entrance passageway to said sump;

separating waste coal tailings from said waste coal slurry by screeningmeans disposed vertically within said entrance passageway;

pumping remaining liquid from said waste coal slurry upwardly along aconduit to a first settling pond located above said underground mine;

transporting said remaining liquid from said first settling pond byforce of gravity to a second settling pond disposed in steppedrelationship adjacent to and below said first settling pond;

transporting said remaining liquid from said second settling pond byforce of gravity to a third settling pond disposed in steppedrelationship adjacent to and below said second settling pond;

transporting said remaining liquid from said third set tling pond byforce of gravity to said station at the surface of said undergroundmine;

combining said remaining liquid with said remaining liquid from saidclean coal slurry and pumping said combined liquid along a conduit tosaid junction box; and

pumping said combined liquid by pump means located adjacent saidjunction box along a plurality of conduits to said underground mines andsaid slurrying devices 2. Apparatus for transporting mined coal from aworking face of an underground mine to a station at the surface of saidmine comprising:

a continuous mobile mining machine operable to dis lodge coal from saidworking face;

conveyor means operably connected to said mining machine to transport amined coal rearwardly of said mining machine;

a continuous mobile slurrying device operably connected to said conveyormeans;

a crusher fixedly mounted to said slurrying device operable to crushmined coal as it is fed into said slurrying device;

a first flexible conduit for supplying carrier liquid to said slurryingdevice for formation of a slurry of crushed coal and said liquidtherein;

a second flexible conduit for transporting said slurry rearwardly ofsaid slurrying device;

a plurality of cleaning table means to separate waste coal tailings fromsaid slurry to form a clean coal slurry and a waste coal slurry. saidcleaning table means comprising a plurality of series connected cleaningtables, the first of said cleaning table in iluid communication withsaid second flexible eonduit and for dividing said slurry into a cleancoal slurry and a Waste coal slurry, and each succeeding cleaning tablereceiving the clean coal slurry formed by the preeeeding cleaning tablefor dividing the received clean coal slurry into a further clean coalslurry and a further waste coal slurry which is combined with the wastecoal slurry from the preceeding cleaning table;

conduit means operable to transport said clean coal slurry rearwardlyfrom said cleaning tables;

a junction box centrally located within said underground mine comprisingmeans for receiving said clean coal slurry and means for receiving asupply of carrier liquid substantially free of coal;

conduit means operable to transport said clean coal slurry from saidjunction box to said station at the surface of said underground mine;

means operable to separate said clean coal slurry into clean coal andremaining carrier liquid;

conduit means for transporting said waste coal slurry away from the lastof said cleaning table means;

a sump operable to receive said waste coal slurry;

means within said sump to separate waste coal tailings from said wastecoal slurry;

conduit means for transporting remaining liquid from said waste coalslurry above said underground mine;

a plurality of settling ponds located above said underground mineoperable to receive said remaining liquid from said waste coal slurry;

means for transporting said remaining liquid from said settling ponds tosaid station at the surface of said underground mine.

means for combining said remaining liquid with said remaining liquidfrom said clean coal slurry;

conduit means for returning said combined liquid from said station atthe surface of mid underground mine to htlltl junction box.

conduit means for returning said combined liquid from said junction boxto said continuous mobile mining machine and said slurrying device.

3. The apparatus as set forth in claim 2 wherein said slurrying devicecomprises:

an open box like structure having a front wall two side walls a rearwall and a bottom constructed so as to be water tight;

at crusher fixedly mounted to said side walls above said box-likestructure having a crusher drum rotably mounted by means of a shaftdriven by a motor said crusher drum covered over its surface by pointedprojections, a crusher box fixedly mounted to said side walls andsurrounding said crusher drum, and a length of pipe horizontally mountedabove said drum having apertures operable to supply liquid to thesurface of said drum;

first pump means operable to pump a carrier liquid from said returnconduit means to said box-like 20 structure and apertured pipe;

second pipe means rearwardly adjacent to said box like structureoperable to pump a slurry formed within said structure away from saidstructure; and 25 continuous belt tracks moveably mounted to saidbox-like structure and operable to supply motion to said structure 4.The apparatus as set forth in claim 2, wherein said cleaning tablescomprise a plurality of end connected units, disposed longitudinally inthe direction of flow of said slurry and constructed in steppedrelationship to one another such that each succeeding unit is of lesserheight than the unit preceeding it.

5. The apparatus as set forth in claim 4, wherein said separation meanscomprises a plurality of horizontally disposed screens within saidcleaning tables.

6. The apparatus as set forth in claim 2, wherein said junction boxcomprises an inner box nested within an outer box. said inner boxoperable to receive said clean coal slurry and said outer box operableto receive said carrier liquid substantially free of coal.

7. The apparatus set forth in claim 2. wherein said sump comprises;

a generally circular pit narrowing at its entrance to form an elongatedpassageway;

a plurality of filter screens vertically disposed along said passagewayoperable to separate waste coal tailings from said waste coal slurry,leaving a remaining carrier liquid; and

a pump located within said pit and operable to remove said remainingcarrier liquid from said pit.

8. A method for transporting mined coal from a working face of anunderground mine to a station at the surface of said mine comprising thesteps of;

dislodging said coal from said working face by means of a mobileunderground mining machine;

conveying said coal from said mining machine to a mobile slurryingdexice;

crushing said coal;

admixing said crushed coal with carrier liquid to form a slurry.

transporting said slurry from said slurrying device to a plurality ofcleaning tables;

lormuig it clean coal lurry and a \iaste coal slurry by renuouig wastecoal and apart ol said carrier liquid from said slurry.

trans utingr said clean coal altlt'tj to a unction box tentrall t locatewithin said underground mine.

transporting said clean coal slurry to a station at the surface of saidunderground mine;

separating clean coal from said clean coal slurry;

transporting said waste coal slurry from said cleaning tables to a sump;

separating waste coal tailings from said water coal I slurry;

transporting remaining liquid from said waste coal slurry to a pluralityof settling ponds located above said underground mine;

transporting said remaining liquid from said settling ponds to saidstation at the surface of said underground mine;

combining said remaining liquid with said remaining liquid from saidclean coal slurry and returning said combined liquid to said junctionbox;

returning said combined liquid from said junction box to said slurryingdevice;

transporting said waste coal slurry from said cleaning tables by pumpingsaid slurry along a conduit to an entrance passageway of a sump;

separating waste coal tailings from said waste coal slurry by verticallydisposed screening means located in said entrance passageway of saidsump;

transporting remaining liquid from said waste coal slurry by pumpingsaid liquid upwardly along a conduit to a first settling pond to asecond settling pond;

transporting said remaining liquid from said second settling pond to athird settling pond; and

transporting said remaining liquid from said third settling pond to saidstation at the surface of said un derground mine.

1. A METHOD FOR TRANSPORTING MINED COAL FROM A PLURALITY OF WORKING FACEOF AN UNDERGROUND MINE TO A STATION AT THE SURFACE OF SAID MINECOMPRISING THE STEPS OF: DISLOGING SAID COAL FROM SAID WORKING FACES BYMEANS OF A MOBILE UNDERGROUND MINING MACHINE, COMBINING SAID COAL WITHCARRIER LI8QUID ADJACENT SAID WORKING FACES, CONVEYING SAID MINED COALAND CARRIER LIQUID BY MEANS OF BIFURATED CONVEYORS TO CRUSHERS FIXEDLYMOUNTED TO MODILE SLURRYING DEVICES, CRUSHING SAID MINED COAL, ADMIXINGSAID CRUSHED COAL WITH ADDITIONAL CARRIER LIQUID TO FROM SLURRIES WITHINSAID SLURRYING DEVIES, TRANSPORTING SAID SLURRIES TO SAID CLEANINGTABLES, FORMING CLEAN COAL SLURRIES AND WASTE COAL SLURRIES WITHIN SAIDCLEANING TABLES BY REMOVING WASTE COAL AND A PART OF SAID CARRIER LIQUIDFROM SAID SLURRIES BY SCREENING MEANS HORIZONTALLY DISPOSED WITHIN SAIDCLEANING TABLES, SUCH THAT CLEAN COAL AND A PART OF SAID CARRIER LIQUIDREMAIN ABOVE SAID SCREENS AND WASTE COAL AND A PART OF SAID CARRIERLIQUID FALL BELOW SAID SCREENS, PUMPING SAID CLEAN COAL SLURRIES ALONGCONDUITS FROM SAID CLEANING TABLES TO A JUNCTION BOX CENTRALLY LOCATEDWITHIN SAID UNDEGROUND MINE, ADMIXING SAID CLEAN COAL SLURRIES WITHINAID JUNCTION BOX TO FROM AN AGGERGATE SLURRY, PUMPING SAID AGGREGATESLURRY AONG A CONDUIT FROM SAID INJECTION BOX TO SAID STATION AT THESURFACE OF SAID UNDERGROUND MINE BY MEANS OF A PUMP LOCATED ADJACENTSAID JUNCTION BOX, SEPARATING SAID SLURRY INTO CLEAN COAL AND CARRIERLIQUID, PUMPING SAID WASTE COAL SLURRIES ALONG CONDUITS AWAY FROM SAIDCLEANING TABLES AND JOINING SAID CONDUTS WITH A SINGLE CONDUIT LEADINGTO THE ENTRANCE PASSAGEWAY OF A SUMP SO AS TO AN AGGREGATE WASTE COALSLURRY, PUMPING SAID AGGREGATE WASTE COAL SLURRY FROM SAID SINGLECONDUIT INTO SAID ENTRANCE PASSAGEWAY TO SAID SUMP, SEPARATING WASTECOAL TAILINGS FROM SAID WASTE COAL SLURRY BY SCREENING MEANS DISPISEDVERTICALLY WITHIN SAID ENTRANCE PASSAGEWAY; PUMPING REMAINING LIQUIDFROM SAID WASTE COAL SLURY UPWARDLY ALONG A CONDUIT TO A FIRST SETTLINGPOND LOCATED ABOVE SAID UNDEGROUND MINE, TRANSPORTING SAID REMAININGLIQUID FROM SAID FIRST SETTLING POND BY FORCE OF GRAVITY TO A SECONDSETTTLING PONF DISPOSED IN STEPPED RELATIONSHIP ADJACENT TO AND BELOWSAID FIRST SETTLING POND; TRANSPORTING SAID REMAINING LIQUID FROM SAIDSECOND SETTLING POND BY FORCE OF GRAVITY TO A THIRD SETTLING PONDDISPOSED IN STEPPED RELATIONSHIP ADJACENT TO AND BELOW SAID SECONDSETTLING POND, TRANSPORTING SAID REMAINING LIQUID FROM SAID THIRDSETTLING POND BY FORCE OF GRAVITY TO SAID STATION AT THE SURFACE OF SAIDUNDERGROUND MINE, COMBINING SAID REMAINING LIQUID WITH SAID REMAININGLIQUID FROM SAID CLEAN COAL SLURRY AND PUMPING SAID COMBINED LIQUIDALONG A CONDUIT TO SAID JUNCTION BOX, AND PUMPING SAID COMBINED LIQUIDBY PUMP MEANS LOCATED ADJACENT SAID JUNCTION BOX ALONG A PLURALITY OFCONDUITS TO SAID UNDERGROUND MINES AND SAID SLURRYING DEVICES. 2.Apparatus for transporting mined coal from a working face of anunderground mine to a station at the surface of said mine comprising: acontinuous mobile mining machine operable to dislodge coal from saidworking face; conveyor means operably connected to said mining machineto transport a mined coal rearwardly of said mining machine; acontinuous mobile slurrying device operably connected to said conveyormeans; a crusher fixedly mounted to said slurrying device operable tocrush mined coal as it is fed into said slurrying device; a firstflexible conduit for supplying carrier liquid to said slurrying devicefor formation of a slurry of crushed coal and said liquid therein; asecond flexible conduit for transporting said slurry rearwardly of saidslurrying device; a plurality of cleaning table means to separate wastecoal tailings from said slurry to form a clean coal slurry and a wastecoal slurry, said cleaning table means comprising a plurality of seriesconnected cleaning tables, the first of said cleaning table in fluidcommunication with said second flexible conduit and for dividing saidslurry into a clean coal slurry and a waste coal slurry, and eachsucceeding cleaning table receiving the clean coal slurry formed by thepreceeding cleaning table for dividing the received clean coal slurryinto a further clean coal slurry and a further waste coal slurry whichis combined with the waste coal slurry from the preceeding cleaningtable; conduit means operable to transport said clean coal slurryrearwardly from said cleaning tables; a junction box centrally locatedwithin said underground mine comprising means for receiving said cleancoal slurry and means for receiving a supply of carrier liquidsubstantially free of coal; conduit means opeRable to transport saidclean coal slurry from said junction box to said station at the surfaceof said underground mine; means operable to separate said clean coalslurry into clean coal and remaining carrier liquid; conduit means fortransporting said waste coal slurry away from the last of said cleaningtable means; a sump operable to receive said waste coal slurry; meanswithin said sump to separate waste coal tailings from said waste coalslurry; conduit means for transporting remaining liquid from said wastecoal slurry above said underground mine; a plurality of settling pondslocated above said underground mine operable to receive said remainingliquid from said waste coal slurry; means for transporting saidremaining liquid from said settling ponds to said station at the surfaceof said underground mine; means for combining said remaining liquid withsaid remaining liquid from said clean coal slurry; conduit means forreturning said combined liquid from said station at the surface of saidunderground mine to said junction box; conduit means for returning saidcombined liquid from said junction box to said continuous mobile miningmachine and said slurrying device.
 3. The apparatus as set forth inclaim 2 wherein said slurrying device comprises: an open box likestructure having a front wall, two side walls, a rear wall and a bottomconstructed so as to be water tight; a crusher fixedly mounted to saidside walls above said box-like structure having a crusher drum rotablymounted by means of a shaft driven by a motor said crusher drum coveredover its surface by pointed projections, a crusher box fixedly mountedto said side walls and surrounding said crusher drum, and a length ofpipe horizontally mounted above said drum having apertures operable tosupply liquid to the surface of said drum; first pump means operable topump a carrier liquid from said return conduit means to said box-likestructure and apertured pipe; second pipe means rearwardly adjacent tosaid box-like structure operable to pump a slurry formed within saidstructure away from said structure; and continuous belt tracks moveablymounted to said box-like structure and operable to supply motion to saidstructure.
 4. The apparatus as set forth in claim 2, wherein saidcleaning tables comprise a plurality of end connected units, disposedlongitudinally in the direction of flow of said slurry, and constructedin stepped relationship to one another such that each succeeding unit isof lesser height than the unit preceeding it.
 5. The apparatus as setforth in claim 4, wherein said separation means comprises a plurality ofhorizontally disposed screens within said cleaning tables.
 6. Theapparatus as set forth in claim 2, wherein said junction box comprisesan inner box nested within an outer box, said inner box operable toreceive said clean coal slurry and said outer box operable to receivesaid carrier liquid substantially free of coal.
 7. The apparatus as setforth in claim 2, wherein said sump comprises: a generally circular pitnarrowing at its entrance to form an elongated passageway; a pluralityof filter screens vertically disposed along said passageway operable toseparate waste coal tailings from said waste coal slurry, leaving aremaining carrier liquid; and a pump located within said pit andoperable to remove said remaining carrier liquid from said pit.
 8. Amethod for transporting mined coal from a working face of an undergroundmine to a station at the surface of said mine comprising the steps of:dislodging said coal from said working face by means of a mobileunderground mining machine; conveying said coal from said mining machineto a mobile slurrying device; crushing said coal; admixing said crushedcoal with carrier liquid to form a slurry; transporting said slurry fromsaid slurrying device to a plurality of cleaning tables; forming a cleancoal slurry and a waste coal slurry by removing waste coal and a part ofsaid carrier liquid from said slurry; transporting said clean coalslurry to a junction box centrally located within said underground mine;transporting said clean coal slurry to a station at the surface of saidunderground mine; separating clean coal from said clean coal slurry;transporting said waste coal slurry from said cleaning tables to a sump;separating waste coal tailings from said water coal slurry; transportingremaining liquid from said waste coal slurry to a plurality of settlingponds located above said underground mine; transporting said remainingliquid from said settling ponds to said station at the surface of saidunderground mine; combining said remaining liquid with said remainingliquid from said clean coal slurry and returning said combined liquid tosaid junction box; returning said combined liquid from said junction boxto said slurrying device; transporting said waste coal slurry from saidcleaning tables by pumping said slurry along a conduit to an entrancepassageway of a sump; separating waste coal tailings from said wastecoal slurry by vertically disposed screening means located in saidentrance passageway of said sump; transporting remaining liquid fromsaid waste coal slurry by pumping said liquid upwardly along a conduitto a first settling pond to a second settling pond; transporting saidremaining liquid from said second settling pond to a third settlingpond; and transporting said remaining liquid from said third settlingpond to said station at the surface of said underground mine.